Intravenous L-5-hydroxytryptophan in normal subjects: an interdisciplinary precursor loading study. Part II: profile of psychotropic effects derived from protocols and psychometric investigations.

L-5HTP was found to act primarily on mood, and unequivocally in the direction of elation. The subjective, protocols, psychometric results, and a double-blind study demonstrated convincingly and intra-individually consistent course of action of the substance under the chosen conditions of application. This course of effects can be described in three phases: In a first phase (about 0 to 1 1/2 hours after end of infusion) an intensive mood elevation (mostly experienced as a disharmonious feeling), psychomotoric activity, changed perception, as well as somatic side effects were observed. A second phase (about 1 1/2 to 3 1/2 hours after end of infusion) was characterized by elevated mood (feeling of well-being) together with a tendency to inactivity, whereas other phenomena were less often reported. A third phase (about 3 1/2 to 6 hours after end of infusion) was characterized by mood decline and the feeling of having again reached "normality". Side effects again tended to occur. It is shown that neither placebo nor situative effects greatly influenced elevation of mood or other substance effects. This is demonstrated by the homogenous time course and the blind studies.